Norwegian versions of the Living with Asthma Questionnaire (LWAQ) and Asthma Bother Profile (ABP), validation and comparison of two asthma groups

Measurement properties of asthma-specific quality-of-life measures: protocol for a systematic review

BACKGROUND

Asthma is a frequent chronic inflammatory disease of the airways, and the assessment of health-related quality of life (HrQoL) is important in both research and routine care. Various asthma-specific measures of HrQoL exist but there is uncertainty which measures are best suited for use in research and routine care. Therefore, the aim of the proposed research is a comprehensive systematic assessment of the measurement properties of the existing measures that were developed to measure asthma-specific quality of life.

METHODS/DESIGN

This study is a systematic review of the measurement properties of asthma-specific measures of health-related quality of life. PubMed and Embase will be searched using a selection of relevant search terms. Eligible studies will be primary empirical studies evaluating, describing or comparing measurement properties of asthma-specific HRQL tools. Eligibility assessment and data abstraction will be performed independently by two reviewers. Evidence tables will be generated for study characteristics, instrument characteristics, measurement properties and interpretability. The quality of the measurement properties will be assessed using predefined criteria. Methodological quality of studies will be assessed using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist. A best evidence synthesis will be undertaken if more than one study have investigated a particular measurement property.

DISCUSSION

The proposed systematic review will produce a comprehensive assessment of measurement properties of existing measures of asthma-specific health-related quality of life. We also aim to derive recommendations in order to help researchers and practitioners alike in the choice of instrument.

TRIAL REGISTRATION

PROSPERO registration number: CRD42014010491.

Cross-cultural adaptation and validation of the Portuguese version of the Living with Asthma Questionnaire

OBJECTIVE

To translate and culturally adapt the Living with Asthma Questionnaire (LWAQ) to the Portuguese language and to test its reliability and validity.

METHODS

The Portuguese version of this disease-specific health-related quality of life measure was obtained with forward/backward translations, consensus panels and a pre-test. The Portuguese LWAQ and Medical Outcomes Study - 36 item Short Form (SF-36) questionnaires, and a form for the characteristics of the patients were administered to 61 subjects with asthma.

RESULTS

Reliability of LWAQ scores was good with Cronbach's alpha coefficients ranging from 0.70 to 0.97 [with the exception of "preoccupation" (0.62) construct, and "sleep" (0.67) and "effects on others" (0.47) domains] and intraclass correlation coefficients between 0.86 and 0.99. Construct validity was supported by the confirmation of predefined hypotheses involving expected significant correlations between LWAQ total, constructs and domains, and SF-36 dimensions with similar content.

CONCLUSION

The Portuguese LWAQ exhibited suitable psychometric properties, in terms of internal consistency, reproducibility and construct validity.

Asthma outcomes: quality of life

BACKGROUND

"Asthma-related quality of life" (QOL) refers to the perceived impact that asthma has on the patient's QOL.

OBJECTIVE

National Institutes of Health institutes and other federal agencies convened an expert group to recommend standardized measures of the impact of asthma on QOL for use in future asthma clinical research.

METHODS

We reviewed published documentation regarding the development and psychometric evaluation; clinical research use since 2000; and extent to which the content of each existing QOL instrument provides a unique, reliable, and valid assessment of the intended construct. We classified instruments as core (required in future studies), supplemental (used according to the study's aims and standardized), or emerging (requiring validation and standardization). This work was discussed at an National Institutes of Health-organized workshop convened in March 2010 and finalized in September 2011.

RESULTS

Eleven instruments for adults and 6 for children were identified for review. None qualified as core instruments because they predominantly measured indicators of asthma control (symptoms and/or functional status); failed to provide a distinct, reliable score measuring all key dimensions of the intended construct; and/or lacked adequate psychometric data.

CONCLUSIONS

In the absence of existing instruments that meet the stated criteria, currently available instruments are classified as either supplemental or emerging. Research is strongly recommended to develop and evaluate instruments that provide a distinct, reliable measure of the patient's perception of the impact of asthma on all of the key dimensions of QOL, an important outcome that is not captured in other outcome measures.

Measuring asthma-specific quality of life: structured review

Measuring quality of life (QoL) has become an increasingly important dimension of assessing patient well-being and drug efficacy. As there are now several asthma QoL questionnaires to choose from, it is important to appreciate their strengths and weaknesses. To assist in this choice, we have reviewed the existing questionnaires in a structured way. Information relating to the conceptual and measurement model, reliability, validity, interpretability, burden, administration format and translations was extracted from the published literature. The instruments differ in almost all criteria considered, and therefore it cannot be assumed that they measure the same thing. We recommend the selection of questionnaires that are designed only for asthma and that do not assess symptoms as part of QoL. Only two of the questionnaires reviewed fulfill these requirements: the Sydney Asthma QoL Questionnaire (AQLQ-S) and the Living with Asthma Questionnaire (LWAQ). However, for multinational studies, it may be convenient or practical to use questionnaires that have been linguistically validated in many languages (AQLQ-J, SGRQ). It remains unclear which of these questionnaires best reflects patient perceptions of QoL. Our review did not involve patients, so for the time being choosing from existing questionnaires requires a compromise based on the rigor of the development process and the target patient group.